The practical applications of Mn3O4 in lithium‐ion batteries are greatly hindered by fast capacity decay and poor rate performance as a result of significant volume changes and low electrical ...conductivity. It is believed that the synthesis of nanoscale Mn3O4 combined with carbonaceous matrix will lead to a better electrochemical performance. Herein, a convenient route for the synthesis of Mn3O4 nanoparticles grown in situ on hollow carbon nanofiber (denoted as HCF/Mn3O4) is reported. The small size of Mn3O4 particles combined with HCF can significantly alleviate volume changes and electrical conductivity; the strong chemical interactions between HCF and Mn3O4 would improve the reversibility of the conversion reaction for MnO into Mn3O4 and accelerate charge transfer. These features endow the HCF/Mn3O4 composite with superior cycling stability and rate performance if used as the anode for lithium‐ion batteries. The composite delivers a high discharge capacity of 835 mA h g−1 after 100 cycles at 200 mA g−1, and 652 mA h g−1 after 240 cycles at 1000 mA g−1. Even at 2000 mA g−1, it still shows a high capacity of 528 mA h g−1. The facile synthetic method and outstanding electrochemical performance of the as‐prepared HCF/Mn3O4 composite make it a promising candidate for a potential anode material for lithium‐ion batteries.
Restricted expansion: The practical applications of Mn3O4 in lithium‐ion batteries are greatly hindered by fast capacity decay and poor rate performance as a result of significant volume changes and low electrical conductivity. A composite composed of Mn3O4 nanoparticles on hollow carbon nanofibers (HCF/Mn3O4) was synthesized by a facile in situ method. The unique nanostructure leads to excellent electrochemical performance (see figure).
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•Deep elimination of diquat dibromide from water has been achieved.•The surface OH and NHx groups are the active sites for the diquat dibromide adsorption.•The mechanism inherent in ...the adsorption-photodegradation of diquat has been explored.
In the study, we present a quick potassium hydroxide heat treatment approach to optimize the “melon” framework of graphite carbon nitride and modify the surface properties by functionalization of hydroxyl groups. The hydroxyl groups functionalized g-CN samples have been applied as bifunctional materials for efficient elimination of diquat dibromide herbicide through synergistic adsorption/photodegradation processes. The structural characterizations of the as-obtained samples, combined with the detailed diquat dibromide herbicide adsorption study, reveal that the surface hydroxyl groups are the active sites for the diquat dibromide adsorption, which account for the much enhanced saturation adsorption capacities of 159.3 mg g−1 at 25 °C and pH = 7 (more than 110 times improvement compared with pristine carbon nitride). Furthermore, the grafted surface hydroxyl groups and optimized planar structures endow the functionalized samples with the advantageous properties of efficient photoinduced charge transfer and separation, low interface resistance, and high photoresponse. Consequently, the deep mineralization of diquat dibromide herbicide was achieved over the bifunctional materials (total removal ratios were ~ 97.1% after 240 min visible-light irradiation). This work not only demonstrates the feasibility of hydroxyl groups functionalized graphite carbon nitride for elimination of herbicide pollutants but also offers new insights to better design efficient and durable materials for environmental remediation.
The gene encoding a single-chain, ribosome-inactivating protein (SCRIP) was cloned from bitter melon (Momordica charantia L.) leaves infected with the fungus, Sphaerotheca fuliginea, by RT-PCR. The ...ORF was 861 bp. The ribosome-inactivating protein was expressed in E. coli and, when purified, it inhibited the growth of the Sphaerotheca fuliginea in vitro. Northern blot analysis revealed that RIP transcripts rapidly accumulated in leaves 1-day post inoculation with Sphaerotheca fuliginea and reached a peak at 3 d. The expression pattern of RIP induced by methyl jasmonate and salicylic acid were different from that of pathogen-induced expression. Mechanical wounding, silver nitrate and osmotic stress stimulated only a slight accumulation of RIP transcripts. Abscisic acid also induced transcription of RIPs. The signal compounds, ethylene and okadaic acid, induced a moderate accumulation of RIP transcripts.
Iron nitrides are considered as highly promising anode materials for lithium-ion batteries because of their nontoxicity, high abundance, low cost, and higher electrical conductivity. Unfortunately, ...their limited synthesis routes are available and practical application is still hindered by their fast capacity decay. Herein, a facile and green route is developed to synthesize Fe4N/Fe2O3/Fe/porous N-doped carbon nanosheet composite. The size of Fe4N/Fe2O3/Fe particles is small (10–40 nm) and they are confined in porous N-doped carbon nanosheet. These features are conducive to accommodate volume change well, shorten the diffusion distance and further elevate electrical conductivity. When tested as anode material for lithium-ion batteries, a high discharge capacity of 554 mA h g−1 after 100 cycles at 100 mA g−1 and 389 mA h g−1 after 300 cycles at 1000 mA g−1 are retained. Even at 2000 mA g−1, a high capacity of 330 mA h g−1 can be achieved, demonstrating superior cycling stability and rate performance. New prospects will be brought by this work for the synthesis and the potential application of iron nitrides materials as an anode for LIBs.
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•Facile and green route is developed for the synthesis of Fe4N/Fe2O3/Fe/PNCN.•Small Fe4N/Fe2O3/Fe nanoparticles are confined in PNCN.•Unique microstructure leads to the excellent electrochemical performance.•High capacity of 389 mA h g−1 after 300 cycles is achieved at 1 A g−1.
High‐energy‐density lithium‐rich layered oxides (LLOs) hold the greatest promise to address the range anxiety of electric vehicles. Their application, however, has been prevented by fast voltage ...decay and capacity fading for years, which mainly originate from irreversible transition‐metal migration and undesirable cathode‐electrolyte interfacial reactions. Herein, a Ti‐based surface integrated layer and bulk doping, which greatly improve the voltage and capacity stability of LLOs is synchronously constructed. More importantly, STEM and Raman results demonstrate that continuous and uniform surface Ti‐based integrated layer is a spinel‐like rocksalt structure with Fd‐3m space group, which is built through by several the replacement of Li ions in surface several atomic layers by Ti ions. After 500 cycles, Ti‐150 sample delivers a capacity retention of 85%, and its voltage decay rate from the 30th to the 500th cycle is only ≈0.72 mV/cycle. Spectral results and DFT calculations suggest that bulk Ti‐doping mitigates the migration of Mn and Ni ions in the bulk, while Ti‐based integrated layer significantly suppresses surface structure evolution and interfacial reactions by impeding the generation of surface Li vacancies during Li extraction as well as preventing direct contact between electrolyte and active materials.
Ti‐based surface integrated layer and bulk doping are synchronously constructed to mitigate the structural evolution and suppresses interfacial reactions of Li‐rich layered cathodes during long‐term cycling. After 500 cycles, Ti‐treated LLO sample delivers a capacity retention ratio of 85%, and its voltage decay rate from the 30th to the 500th cycle is only ≈0.72 mV/cycle.
The development of novel manganese vanadate electrode materials with high capacity and good rate capability is a great challenge. In this work, a novel manganese vanadate grown on reduced graphene ...oxide is successfully prepared by a fast and facile approach. Small Mn2.1V0.9O4 particles (20–50 nm) are anchored on reduced graphene oxide, which significantly alleviates volume changes and improves electrical conductivity and lithium ion transfer. In addition, the strong chemical interactions between Mn2.1V0.9O4 and reduced graphene oxide are conducive to accelerate charge transfer. These features are favorable for achieving high reversible capacity and excellent rate performance. As an anode for lithium-ion batteries, a high discharge capacity of 981 mA h g−1 is retained after 80 cycles at 100 mA g−1. Even at 2000 mA g−1, a high capacity of 748 mA h g−1 is achieved. New prospects are brought by this work for the synthesis and the potential application of manganese vanadate materials.
•Novel Mn2.1V0.9O4/rGO composite is prepared by a fast and facile route.•Small Mn2.1V0.9O4 nanoparticles are chemically anchored on rGO.•Unique nanostructure leads to the excellent rate performance.•High capacity of 748 mA h g−1 is achieved at 2 A g−1.
The development of intercalation-type V2O3 in lithium-ion batteries is greatly hindered by low reversible capacity, poor cycling stability and rate performance. It is believed that fabricating ...V2O3/3D carbon framework composite will bring about a superior electrochemical performance. Facile synthesis of this composite, however, is a great challenge. In this work, a facile strategy is developed to synthesize V2O3/porous N-doped 3D carbon nanosheet framework composite. The obtained V2O3 nanoparticles are grown in porous N-doped 3D carbon nanosheet framework, which can significantly elevate electrical conductivity, Li+ ion transfer and electrode stability. What's more, the strong chemical interactions between V2O3 and carbon are conducive to accelerate charge transfer. These features of V2O3/porous N-doped 3D carbon nanosheet framework composite are favorable for achieving high reversible capacity and excellent rate performance. When used as the anode for lithium-ion batteries, a high discharge capacity of 436 mA h g−1 is retained at 500 mA g−1 after 200 cycles. Even at 2000 mA g−1, a capacity of 344 mA h g−1 is achieved. This work will bring the new prospects for the synthesis and the potential application of metal oxide/3D carbon framework composite.
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•V2O3/PNCNF composite was synthesized by a facile method.•V2O3 nanoparticles are grown in PNCNF and give a strong interaction with PNCNF.•Unique structure leads to the excellent electrochemical performance.•High capacity of 344 mA h g−1 is achieved at 2 A g−1.
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Li-rich layered oxide materials possess high voltage and high specific capacity, which makes them attractive cathode candidates for lithium-ion batteries. However, they still suffer ...from a poor rate capability, which seriously blocks their widespread practical applications. In this work, Li(Li0.167Mn0.5Co0.167Ni0.167)O2 microspheres were synthesized by a hydrothermal-assisted method, in which Ni-Co-Mn-based microspherical precursors obtained by a hydrothermal process with polyethylene glycol-600 (PEG-600) as a surfactant were mixed with lithium sources and then sintered to yield the final products. It is found that the as-prepared Li-rich layered oxide microspheres exhibit high discharge capacity and superior rate performance: delivering an initial discharge capacity of 292mAhg−1 at a current density of 20mAg−1, 189mAhg−1 at a current density of 600mAg−1 and 142mAhg−1 at a current density of 2000mAg−1 (10C), which are better than that of the sample as-prepared by co-precipitation method. The high discharge capacity and improved rate-capability were beneficial from the microspheres assembled by uniform primary particles around 250nm, more reversible redox and better electrode kinetics comparing to that of the co-precipitation sample. The preparation strategy reported here may offer hints for achieving various advanced Li-rich layered composite materials that would be used in high-performance energy storage.
Lycopene as a natural antioxidant that have been studied for ultraviolet radiation (UVR) photo protection and is one of the most effective carotenoids to scavenge reactive oxygen species (ROS). This ...review aims to summarize the protective effect of tomato and lycopene on skin photo damage and skin photoaging in healthy subjects by reviewing the existing population intervention experiments. A total of five electronic databases including PubMed, Scopus, EBSCO, Web of Science and Cochrane Library were searched from inceptions to January 2021 without any restriction. Out of 19336 publications identified, 21 fulfilled the inclusion criteria and were meta-analysis. Overall, interventions supplementing tomato and lycopene were associated with significant reductions in Δa*, MMP-1, ICAM-1 and skin pigmentation; while tomato and lycopene supplementation were associated with significant increase in MED, skin thickness and skin density. Based on the results of this systematic review and meta-analysis, supplementation with tomato and lycopene could reduce skin erythema formation and improve the appearance and pigmentation of the skin, thereby preventing light-induced skin photodamage and skin photoaging. Lycopene-rich products could be used as endogenous sun protection and may be a potential nutraceutical for sun protection.
•Cobalt-free NaxLi1.2-xMn0.6-xAlxNi0.2O2 oxides are prepared by a sol-gel method.•Dual-doping strengthens the covalence of Mn-O bonds and suppresses the side reactions between cathode and ...electrolyte.•Doped cathode has a capacity retention over 92.2% after 100 cycles at a high temperature of 55°C.
Li-rich cobalt-free oxides, popularly used as a cathode with high capacity in lithium ion battery, always suffer from poor cycling stability between 2.0 and 4.8V vs Li+/Li, especially when cycled at high temperatures (>50°C). To overcome this issue, Na+ and Al3+ dual-doped NaxLi1.2-xMn0.6-xAlxNi0.2O2 Li-rich cathode is prepared in this study. It is shown that the side reactions between cathode and electrolyte during cycling are suppressed. The improved cycling performance is observed for all of the doped samples, among which the sample with x=0.03 exhibits the highest capacity retention of 86.1% after 200 cycles between 2.0 and 4.8V at 2C (1C=200mAg−1) and shows a remarkable cycling stability, even at a high temperature of 55°C (a capacity retention of 92.2% after 100 cycles). Moreover, the average voltage of the sample with x=0.03 after 100 cycles at 0.5C remains at 3.11V with a retention ratio of 86.6%. This work provides a new strategy to develop Li-rich cobalt-free cathodes with excellent cycling stability for lithium ion batteries at high temperatures.
